When
3:45 p.m., April 8, 2014
Where
Kuiper Space Sciences 312
Dr. Tommi Koskinen
Research Assistant
University of Arizona - Lunar and Planetary Laboratory
The upper atmosphere of Saturn from Cassini/UVIS occultations
Abstract:
Despite significant advances enabled by the Pioneer and Voyager missions, our general understanding of the upper atmospheres on the giant planets in the solar system is still relatively poor. The temperatures in the thermospheres are much higher than expected, dynamics is practically unconstrained by observations, and only a few density profiles of the minor species are available to constrain photochemistry. In this sense, solar and stellar occultations by Saturn that are observed by the Cassini UVIS instrument provide much needed constraints on models of the atmosphere ranging from the stratosphere to the exobase. In particular, the spatial and temporal coverage of the data allow for the identification of trends indicative of dynamics and energy deposition. The analysis of these observations, however, poses unique challenges that can lead to significant confusion over their interpretation. I will review some of these challenges and present results from more than 30 occultations, including new evidence that points to an unexpected expansion of Saturn's equatorial thermosphere.
Research Assistant
University of Arizona - Lunar and Planetary Laboratory
The upper atmosphere of Saturn from Cassini/UVIS occultations
Abstract:
Despite significant advances enabled by the Pioneer and Voyager missions, our general understanding of the upper atmospheres on the giant planets in the solar system is still relatively poor. The temperatures in the thermospheres are much higher than expected, dynamics is practically unconstrained by observations, and only a few density profiles of the minor species are available to constrain photochemistry. In this sense, solar and stellar occultations by Saturn that are observed by the Cassini UVIS instrument provide much needed constraints on models of the atmosphere ranging from the stratosphere to the exobase. In particular, the spatial and temporal coverage of the data allow for the identification of trends indicative of dynamics and energy deposition. The analysis of these observations, however, poses unique challenges that can lead to significant confusion over their interpretation. I will review some of these challenges and present results from more than 30 occultations, including new evidence that points to an unexpected expansion of Saturn's equatorial thermosphere.
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